Packing of hypodermic needle assembly



A rilzl, 1969 'lcHl'Ro ISHII 3,435,944v PACKING OFHYPODERMIC NEEDLEASSEMBLY Filed July 10. 1967 E MEU M I INVENTQR. E

United States Patent US. Cl. 206-43 2 Claims ABSTRACT OF THE DISCLOSUREA packing for a hypodermic needle assembly comprising a covering ofsynthetic resin film having a dome portion to hold a hypodermic needleassembly, a base plate which consists of a paper sheet fastened to thecovering so as to seal the dome portion and a synthetic resin filmhaving a large number of micropores and attached to the surface of thepaper sheet.

Background of the invention This invention relates to a packing ofhypodermic needle assembly to hold the needle under a sterile condition,more particularly to an improved packing of such needle assembly whichpermits easy sterilization of the interior thereof and also enables ahighly sterilized condition to be maintained until said packing isopened.

The packing including a hypodermic needle assembly under a sterilecondition generally consists of a base plate made of paper and asynthetic resin film having a dome portion formed in the central partattached to said base plate in order to hold said needle assembly, suchpacking is commonly known as blister packing. The needle assembly heldin the dome usually comprises a shield such as a plastic sheath in orderto protect the cannula portion of the assembly. This shield also servesthe purpose of preventing the cannula from being touched by the handwhen a needle assembly is fitted to the syringe after being taken out ofthe packing.

Such packing is completed when sterilization is carried out byintroducing sterilizing gases such as ethylene oxide into the interiorafter mounting a needle assembly therein. The paper constituting a baseplate allows the sterilizing gas to permeate therethrough at the time ofsterilization and acts as a filter to prevent bacteria from beingintroduced into the interior after sterilization. However, such afiltering action can occur only when the paper is in a dried condition.When the paper becomes wet by absorbing moisture, bacteria presenttherein will easily permeate into the interior of the packing along withthe moisture attached to the interstices between the paper fibers, thusconsiderably degrading the sterile condition of the needle assemblycontained therein. Furthermore, wetting will reduce the mechanicalstrength of paper, thus the packing will be damaged during handling.

Summary of the invention This invention provides a packing for ahypodermic needle assembly which has a synthetic resin film having alarge number of micropores disposed on the surface of the base plate.The synthetic resin film has a considerably better water repellency thanpaper, so that the film effectively prevents moisture from penetratinginto the paper when the packing is exposed to the moisture, and yetallows sterilizing gases to get into the packing through said numerousmicropores bored in the film at the time of sterilizing treatment.

It is therefore one object of this invention to provide a novel packingfor a hypodermic needle assembly which has good permeability tosterilizing gases at the time of sterilizing the packing and alsoprevents bacteria from getting into the interior even when the packingcomes in contact with moisture.

Another object of this invention is to provide a packing assembly, thebase plate of which is protected from damage even when the packing iswetted.

Brief description of the drawing FIG. 1 is a perspective view of apacking according to this invention; and

FIG. 2 is an enlarged sectional view of the packing taken along the lineII-II in FIG. 1.

Description 0 the preferred embodiment Referring now to the accompanyingdrawing, a packing of hypodermic needle assembly according to thisinvention illustrated in FIGS. 1 and 2 comprises a base plate 4consisting of a paper sheet 1 and a synthetic resin film 3 attached toone surface of said paper sheet and having a large number of micropores2, a transparent covering 8 consisting of high mechanical strength. suchas polycarbonate resin fastened to the paper sheet 1 of said base plateby a heat sealed synthetic resin film 7 such as polyethylene, and ahypodermic needle assembly 9 enclosed in said dome portion 5 of saidcovering 8.

The covering 8 should have sufiicient mechanical strength such astension or bending strength, polycarbonate resin is Very suitable forthis purpose. Where a material of low heat seal properties such aspolycarbonate is used in covering 8, it is preferable to insert athermoplastic material such as polyethylene between said covering andpaper sheet 1 in order to supplement the heat seal adhesivitytherebetween. However, polyethylene film can be omitted in case amaterial of good heat seal properties is used for covering 8, or in caseadhesion between covering 8 and paper sheet 1 is performed by means ofapplication of adhesive material.

It is necessary that the paper sheet 1 permits gases to permeate throughthe interstices between the fibers, and prevents bacteria from passingtherethrough. Permeability of bacteria through the paper sheet dependsupon the compactness of fibers and the thickness of the paper sheet.Kraft paper which is known to have a compact and uniform structure ispreferable for this purpose, Where such paper sheet has a thickness ofabout 100 microns, it will be sufficiently protected that bacteriapermeates the paper sheet by its filter effect.

To one surface of the paper sheet is attached the syn thetic resin film3 which has a large number of micropores bored therethrough, and istightly attached to the paper sheet at the edge thereof by means of anadhesive material or heat seal. Consequently, even when the packing iswetted with water, the film 3 prevents the paper sheet 1 from beingexposed to moisture, and when the packing undergoes sterilization thefilm 3 permits sterilizing gases to permeate through the microporesbored so that these gases can be easily introduced into the interior ofdome 5 by passing through the paper sheet 1. Decreasing the diameter ofthe micropores 2 provided in said film 3 gives a greater advantage inthat a quantity of moisture passing the film is decreased. However, itis diificult and impracticable to bore micropores of an extremely smalldiameter of less than 0.05 mm., for example, and it is unnecessaryindeed to provide so fine micropores. Generally, micropores with adiameter of 0.1 mm. or less would not permit the passage of moistureunless a high pressure is applied.

The distribution density of the micropores 2 bored in film 3 regulatesthe rate at which sterilizing gases permeate into the dome 5 at the timeof sterilizing treatment. Under ordinary sterilizing conditions the airin the dome is substituted with sterilizing gases such as ethyleneoxidecontaining 60 to of moisture in relative humidity. Sterilization iscarried out by maintaining the interior of said dome in this conditionfor desired length of time. To carry out suificient sterilizationwithout modifying the ordinary sterilizing conditions, it will be enoughif sterilizing gases permeate at the rate of about 1 ml./sec. at apressure of about 300 g./cm. If a film has micropores of 0.1 mm.diameter at the rate of one micropore per square millimeter, the filmwill permit the aforementioned rate of gas permeation.

There are various ways of boring micropores in a film with theaforementioned distribution density. One of the most appropriate mannerconsits in passing a film over the entire surface of a rotating rollerhaving needles of the desired small diameter planted upright with thedesired distribution density in such a manner that said film is pressedthereto, thus enabling said film to be bored with micropores of thedesired diameter and distribution density. The film thus bored is placedand fastened to a paper sheet by means of joining such as heat seal.

Experiments were made to investigate the ability of these joined filmand paper to prevent the permeation of bacteria when it was moistened.The samples used consisted of a sheet of bleached kraft paper 100microns thick and a laminated sheet comprising the same paper sheet anda polyethylene film to 40 microns thick attached to one surface of saidpaper, said film having circular micropores about 0.1 mm. in diameterbored at the rate of one micropore per square millimeter. Both sampleswere folded in such a manner that they formed a rectangular dish (in thelaminate, in such a manner that the samples constituted the outside ofthe dish) and then subjected to sterilizing treatment. Two types ofliquid were prepared: (1) supernatant liquid obtained after solidssettled down in a suspension dispersed a given amount of soil in waterand (2) liquid comprising part of said supernatant liquid added to aliquid culture medium in order to culture the bacteria contained in theformer. Each of these two types of liquid was mixed, the mixed liquidthus obtained was poured into separate dishes of both samples, each ofsaid samples was floated on separate fresh liquid culture media, andthen taken off one minute later, each of the liquid culture medium waspreserved for further cultivation of bacteria, respectively. The culturemedia with the sample comprising only paper was observed to havediscoloration due to the proliferation of bacteria, whereas the culturemedium used with the laminated sample showed no evidence of bacteria.Next, the laminate sample dish was made to float on a liquid culturemedium for 3 hours, while holding a bacteria-bearing liquid in it. Afterremoving the dish, said liquid culture medium was observed as describedabove, but still it presented no existence of bacteria.

As mentioned above, the packing of hypodermic needle assembly hasconsiderably improved its sterile condition even under the moistenedcondition undesirable for its storage, so that it can be usedeffectively at localities lacking sterilizing equipment such as affectedareas Without concern over the degradation of its sterile state.Moreover, the synthetic resin film involved in this package of thisinvention which has a large number of fine micropores presents nodifficulties in sterilizing the subject packing and also the cost of thefilm is negligibly low as against that of the whole packing, so that itwill not afiect the efficiency of manufacturing the packing and theoverall cost thereof.

What is claimed is:

1. An assembly for packing of a hypodermic needle comprising:

a paper sheet;

a synthetic resin film having a large number of micropores of less than0.1 mm. in diameter bored therethrough, there being at least onemicropore per square millimeter of synthetic resin film surface, topermit gas permeation of said film, said film being laminated to onesurface of said paper sheet;

a covering of gas-impervious film fixed, except its central portion, tothe opposite surface of said paper sheet to form a central hollowportion between said paper sheet and covering;

and a hypodermic needle inserted into a sheath and enclosed in thecentral hollow portion.

2. The packing of hypodermic needle assembly according to claim 1wherein said base plate permits gas permeation through said microporesat the rate of at least 1 mL/sec. at a pressure of 300 g./cm.

References Cited UNITED STATES PATENTS 2,997,224 8/ 1961 Stannard 229-533,074,540 l/1963 Beich et a1. 206-43 3,253,705 5/1966 Stoker 206-2,892,538 6/1959 Middleton, et a1. 206-43 FOREIGN PATENTS 1,152,4759/1957 France.

JOSEPH R. LECLAIR, Primary Examiner.

